A sliding device is a device which bears the fifth wheel coupling and allows the coupling to be adjusted in the longitudinal direction of the vehicle and in particular to be moved into various positions.
After adjusting the sliding device, particularly during a trip, it might occur that the driver will forget to lock the sliding device mechanism so as to hold the fifth wheel coupling in a given position. This may lead to uncontrolled shifting during travel, and to hazardous situations. E.g., when traveling on a steep downhill grade or when undergoing braking, the front of the semi-trailer may strike the cab of the tractor.
Additionally, with known sliding devices, problems may occur relating to distribution of the load to various axles, and relating to the overall length of the tractor-semitrailer combination. Improper load distribution may affect driving characteristics, may cause excess tire wear, and may lead to undesirable loading of axles whereby allowed limits are exceeded. The length of the tractor-semitrailer aggregate may come to exceed legal limits. If the tractor-semitrailer aggregate is too short, the front of the semi-trailer may collide with the tractor cab or chassis, on turns. A further drawback of known sliding devices is that substantial driver time and effort are consumed in adjusting the length of the tractor-semitrailer aggregate, with the driver having to alight from and reenter the cab multiple times to check the changed length. This adversely affects the economic advantages of employing a sliding device in the first place.
Sliding devices are known, e.g. from DE AS 1780488, EP 0503954 A1, and DE 19944684 C1.
Further, U.S. Pat. No. 6,736,420 B2 discloses a sliding device wherein a sliding device which bears the fifth wheel coupling is slidably mounted on two guide rails equipped with toothed beams. The slide bears a locking device comprising locking pieces which engage the toothed beams.
One of the locking pieces is connected to an opening lever, and the other locking piece is connected to a locking piece lever member, wherewith the opening lever and locking piece lever member are themselves interconnected. The opening lever is connected to an actuating device, which may be, e.g., a pulling-handle bar for manual actuation or an actuator driven by a pressure medium. In the open condition, the two lever elements assume a bent (unaligned) position, and in the locked condition the two lever elements assume a straightened (aligned) position. With this known sliding device it is necessary for the driver to visually monitor the position of the slide before he begins driving.